FIG. 1 is a perspective view of a cellular phone equipped with a conventional capacitive touch sensor module 110, and FIG. 2 is a cross sectional view of the cellular phone in which the touch sensor is installed.
A conventional cellular phone 100 includes an upper casing 101, a touch sensor module 110, and a lower casing 102. In the upper casing 101 a support member 101a is formed surrounding a center opening, and the touch sensor module 110 is installed on the support member 101a. A switch button 120 is installed on a front face of the upper casing 101. A display 140 and a main printed circuit board (PCB) 150 are installed inside the lower casing 102. The display 140 is disposed beneath the touch sensor 110. Even though being not shown in the drawings, a flexible printed circuit (FPC) for signal transmission is electrically connected to the touch sensor module 110 and the main PCB 150. A speaker 130 is installed in the upper casing 101, and a microphone 140 is installed on an external surface of the upper casing 101.
One of recent structural design trends is to make the level of the front face of the touch sensor even with that of the upper casing in order to ease assembly operation and attain a better esthetic view. For this purpose, the support member 101a is formed in such a manner that a step having the same height as the thickness of the touch sensor module 110 is provided at the perimeter of the center opening. The front face of the touch sensor module 110 can be divided into a transparent window area W for showing an image to be displayed through the display 140 and a decoration region D surrounding the window area. The transparent window area W is used also for receiving touch inputs. The decoration region D is used for printing a trademark or a logo of a phone manufacturer while hiding opaque interconnection pattern residing in the vicinity of an edge of the touch sensor.